should be it

external/duckdb/test/sql/timezone/disable_timestamptz_casts.test

@@ -0,0 +1,60 @@
+# name: test/sql/timezone/disable_timestamptz_casts.test
+# description: Test for disabling timestamp => timestamptz casts
+# group: [timezone]
+
+# Setting has no effect when ICU is not loaded as the two types are equivalent
+statement ok
+set disable_timestamptz_casts=false;
+
+query I
+select cast('2020-01-01T00:00:00'::timestamp as timestamptz)
+----
+2020-01-01 00:00:00+00
+
+query I
+select cast('2020-01-01T15:00:00+0000'::timestamptz as timestamp)
+----
+2020-01-01 15:00:00
+
+statement ok
+set disable_timestamptz_casts=true;
+
+query I
+select cast('2020-01-01T00:00:00'::timestamp as timestamptz)
+----
+2020-01-01 00:00:00+00
+
+query I
+select cast('2020-01-01T15:00:00+0000'::timestamptz as timestamp)
+----
+2020-01-01 15:00:00
+
+# With ICU loaded, the casts are disabled in both directions when the flag is set.
+require icu
+
+statement ok
+set calendar='gregorian';
+
+statement ok
+set TimeZone='America/Los_Angeles';
+
+statement ok
+set disable_timestamptz_casts=false;
+
+query I
+select cast('2020-01-01T00:00:00'::timestamp as timestamptz)
+----
+2020-01-01 00:00:00-08
+
+statement ok
+set disable_timestamptz_casts=true;
+
+statement error
+select cast('2020-01-01T00:00:00'::timestamp as timestamptz)
+----
+Casting from TIMESTAMP to TIMESTAMP WITH TIME ZONE without an explicit time zone has been disabled
+
+statement error
+select cast('2020-01-01T15:00:00+0000'::timestamptz as timestamp)
+----
+Casting from TIMESTAMP WITH TIME ZONE to TIMESTAMP without an explicit time zone has been disabled